China's disputed selection as the Panchen Lama has espoused Buddhist philosophy in a speech that was his first appearance outside the mainland and showed greater efforts by Beijing to gain acceptance of its rule over Tibet.

The Panchen Lama is Tibetan Buddhism's second-highest spiritual leader, but followers of the exiled Dalai Lama do not recognise China's choice.

He spoke at the third World Buddhist Forum in Hong Kong, a showcase for China's cultural diplomacy attended by more than 1,000 monks, nuns and scholars from 50 countries. China holds the forum every three years and the Panchen Lama's attendance was aimed at burnishing his religious credentials.

Buddhist theory is "sweet dew that ends human suffering and is a way to promote world peace", said the Panchen Lama, who wore a crimson robe.

He criticised "materialistic technology" in his eight-minute speech and said greed had "unbalanced the ecosystems, contaminated the environments, caused natural disasters, spread epidemics, induced wars and hence endangered all sentient beings now and in future", according to an official translation of his speech.

Before the speech, he and other Buddhist leaders bowed three times before a 2,500-year-old bone fragment said to be part of the Buddha's skull.

Beijing installed the then six-year-old Gyaltsen Norbu as the Panchen Lama in 1995 while rejecting another boy chosen by the Dalai Lama. That boy has not been seen since.